Large diesel engines such as used in railroad locomotives, heavy earth-moving equipment and the like, can be difficult to start, particularly at low operating temperatures. Starting the diesel engines requires a large amount of electrical energy. The only source of electrical energy may be a bank of batteries whose ability to produce large amounts of energy is also adversely affected by low ambient temperature operating conditions. If the energy from the batteries is insufficient for starting, auxiliary power must be available. For these and other reasons, it is the practice to leave the engine running when not in use, particularly where the locomotive is in a yard or siding and auxiliary power is not readily available. However, a locomotive may burn in the order of 6 to 8 gallons per hour, resulting in a substantial wasted fuel cost when measured in terms of the number of hours of locomotive non-use.
Various systems have heretofore been proposed to maintain an engine heated even though it has been shut down. For example, U.S. Pat. Nos. 4,245,593 and 4,249,491 show an arrangement for using an electric heater for preheating both the lubricating oil and the coolant of an engine to make it easier to start. Such an arrangement, however, requires access to a source of electrical power, which may not always be available. Using the heat from another engine has also been proposed by providing a temporary connection between the two liquid cooling systems for transferring heat from one engine to another. See, for example, U.S. Pat. Nos. 3,373,728 and 4,051,825. Problems arise with such arrangements, including the possibility that the engine will be started and driven off with the heated water systems still attached. Trade union restrictions may also require special personnel to make the necessary interconnection. It also requires that another engine equipped with suitable connecting attachments be available.